Novel Converter Concept for Bearingless Slice Motor Systems

The general trend towards smaller and more economical designs has also reached bearingless slice motor (BSM) systems. Up to now, full-bridge converters have been used in order to independently control the phases of the active magnetic bearing and the drive system. In this paper, a simplified topology based on three half-bridges is proposed to replace two conventional full-bridges. With this, the number of required power semiconductors is reduced by 25%. The three half-bridges can be advantageously realized by one integrated IGBT module, thus achieving a reduction of the total converter volume by 43% as compared to a discrete full-bridge solution. The principle of operation is explained and analytical expressions for the calculation of the current stresses on the power components and dc-link capacitors are provided as a basis for a design of the system. Finally, the performance of the system is shown for a 600W prototype of the topology.